Step 3.5 Flash 2603 2026: Benchmarks, Pricing & Full Specs

Name: Step 3.5 Flash 2603
Brand: StepFun
Price: 0.1 USD

Specifications

AA Intelligence Index

17.0

Artificial Analysis · 4.3 · 10/27/2026, 3:00:24 PM

Context Window

262K tokens

Input Price/1M

$0.10

#49 of 445

Output Price/1M

$0.30

Parameters

—

Max Output

66K tokens

Cost per Task

—

USD / task · lower is better · Artificial Analysis · 4.3 · 10/27/2026, 3:00:24 PM

Benchmarks

Artificial Analysis metrics for Step 3.5 Flash 2603. Higher is better for capability indexes; lower is better for cost per task.

overall

Benchmark	Score	Maximum	Methodology	Source / version / date
AA Intelligence Index	17.0	100.0	Artificial Analysis official API	Artificial Analysis · 4.3 · 10/27/2026

Information

Release date: April 02, 2026
Tool Calling: ✅ Supported
Vision: ❌ Not supported
Audio: ❌ Not supported

Full Analysis: Step 3.5 Flash 2603

What is Step 3.5 Flash 2603?

Step 3.5 Flash 2603 is an AI model developed by StepFun, classified as a large language model (LLM). It focuses on text processing and natural language generation. As an open source model, it is available for download, customization, and on-premises deployment. With a context window of 262K tokens, it is suitable for processing long documents such as contracts, books, and complete codebases.

Pricing & Costs in 2026

Step 3.5 Flash 2603 is usage-based, priced at $0.1/1M input tokens and $0.3/1M output tokens. For context: 1 million tokens is approximately 750,000 words, or about 10 average-length books. At this aggressive price point, it is one of the most cost-effective options on the market, ideal for high-volume applications like chatbots, bulk document analysis, and automation.

Benchmarks & Performance

Step 3.5 Flash 2603 was evaluated on 1 different benchmarks, covering categories like overall. Results show moderate performance across available evaluations.

It's important to note that benchmarks measure specific aspects and don't capture the full user experience. Factors like instruction adherence, behavior in long conversations, and real-world task quality vary significantly between models and aren't always reflected in standard scores.

Recommended Use Cases

Step 3.5 Flash 2603 is suitable for a wide range of AI applications: long document analysis (contracts, legal proceedings, codebases), automation with tool calling (API integration, databases, external systems), high-volume chatbots and automated support, complex reasoning, math problem solving, and logical analysis, text generation, summarization, translation, and general assistance.

Comparison with Alternatives

In the 2026 AI model ecosystem, Step 3.5 Flash 2603 competes directly with similarly capable models. StepFun competes in this segment against OpenAI, Anthropic, Google, and Meta. The choice between models depends on the specific use case, budget, latency requirements, and need for features like multimodality and tool calling.

For a detailed side-by-side comparison, use our comparison tool or check the overall model ranking.

Frequently Asked Questions

What is Step 3.5 Flash 2603?

Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....

How much does Step 3.5 Flash 2603 cost?

Step 3.5 Flash 2603 costs $0.1/1M input tokens and $0.3/1M output tokens. For heavy usage (e.g., a chatbot handling 100k messages/month), costs can range from $10 to $1,000 depending on volume.

How does Step 3.5 Flash 2603 compare with other models?

In available benchmarks, Step 3.5 Flash 2603 scored: AA Intelligence Index: 17/100. See the full table above for a detailed comparison.

Is Step 3.5 Flash 2603 open source?

Yes, Step 3.5 Flash 2603 is an open source model. You can deploy it on-premises, customize it via fine-tuning, and maintain full control over your data. Check the official repository for the specific license.

What is Step 3.5 Flash 2603 best for?

Step 3.5 Flash 2603 excels at complex reasoning and problem solving. With its large context window, it handles long documents, codebases, and extended conversations. It supports tool calling for API integrations and automation.